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Rotor pack/gear plate swap how to...

Well, it looks like I'll be swapping my rotor pack myself. I don't mind doing it, but hadn't planned on being the one to do it. As we all know, plans change. Anyhow, I am swapping late model coated rotors into my MPII. I have searched and found posts detailing similar swaps, but I feel they go into more detail and work than is needed for my situation (baking/freezing/pressing parts) and therefore I don't know which components of the process I need to follow and which ones are not necessary. I say this b/c I don't believe I need to replace any bearings/seals as my blower has only 75 miles on it since the MPII conversion/rebuild. SO, what I need to know is what do I have to do to merely swap the rotor pack/gear plate assembly? Do I need to replace any seals while doing this? (I'm working on a 75-mile old rebuild.)

It's easy if that's all you are doing. Just take the snout off then with a rubber mallet gently tap the rotors. (this is the inch or so that the snout but up against.) You just need to do it enough to loosen the rotors up enough to get them to pull out. Then slide in the new ones, bolt up the snout (don't forget to line up the coupler, otherwise it won't go together) and fill up with supercharger oil. That's it. You don't even have to pull the pulley off. I would seal up the mating surfaces with some rtv sealant, just to keep everything nice and tight. Be careful though on the rotor side so you don't get any of that rtv into to rotors...not that it would really damage the rotors, but it's just better to keep as much as you can out of the rotor/case. Easy job and shouldn't take more than about 30 minutes to complete.

Seal the rotor pack? Do you mean the 1" thick gear plate attached to the front of the pack? Can't I just use Ford gasket maker? Takes about 8oz to refill the SC correct? One more thing, dare I reuse the oil? It only has 75 miles of use or so on it.

Seal the rotor pack? Do you mean the 1" thick gear plate attached to the front of the pack? Can't I just use Ford gasket maker? Takes about 8oz to refill the SC correct? One more thing, dare I reuse the oil? It only has 75 miles of use or so on it.

P.S. David, luckily the SC is off the car.

He's talking about sealing the plate of the rotor pack to the blower case on one side and sealing it to the oil filled snout on the other side. The side that seals to the snout isn't nearly as critical as the blower case side.

To prevent excessive clearance on the ends of the rotors (inlet end), you must not use a sealer that is too thick. I use RTV and spread out in a very thin coat, but the loctite mentioned earlier would be better.

I would also suggest test fitting the rotors before adding sealer and bolting it back together, to make sure the rotors turn freely. You will also want to recheck the rotors after bolting the blower together and especially after bolting down to the intake manifold to make sure it still turns freely.

In some rare instances where the rotor tip to case clearance is very close (less than .002) the slight amount of case distortion from bolting the blower down to the intake manifold will cause the rotors to bind. If this happens it will be necessary to use shim stock between the blower mounting bosses and the blower case stacked in amounts necessary to remove the distortion.

This mod is by far my favorite, please tell us the results afterwards.

If by results you mean HP gain, unfortunately there is no way I'll know as I am changing several things simultaneously. One thing I am doing differerently, b/c of the rotor pack change, is I'll be overdriving the MPII 15% instead of the planned 20% due to the increased efficiency, plus this will give me a place to step up to in the future (20%) if things pan out.

However, if by results you mean, how did it go for me, by all means I'll share what i hope to be my success story. I am having a time finding Loctite 518. I called two Napa stores and they couldn't find it. The third cross referenced Permatex (owner of Loctite) sealer 518-13, so I'll ASSume that is the same. The description of it is an anerobic gasket maker. More to come, can't wait to open 'er up.

Since there seems to be lots of interest in the coated rotor swap I think I might make a how to. I am currently helping my friend put a 94/95 sc on his 89. I did some porting on the blower and bought a set gtp rotors to put in it. So since its all apart I can take pictures along the way and make a how to. Ive also put the gtp rotors in my MPII so I have a clue as to whats involved.